With the rapid development and progress of information technology, the consumer electronic products, such as portable storage and video/audio media, are widely used in the fields of data read/write and video image. Generally, the universal serial bus (USB) protocol is utilized as a communication bus which is served as the communication interface between the electronic product and the host unit. The USB protocol is developed from version 1.0 to version 3.0 in order to speed up the read/write process of the data stream of the electronic product. The USB 3.0 gradually becomes a standard interface for high-speed data transmission of the electronic product for increasing the access efficiency of the data.
The receiver and transmitter of the electronic product receive the information from the host unit (e.g. computer system) or transmits message to the host unit based on USB 3.0. It is necessary to detect the impedance between the host and the electronic product before the serial signal is transmitted at high-speed operation frequency. The serial signal is not transmitted until the impedance between the host and the electronic product is matched.
The impedance matching step includes that the circuit impedance if the electronic product is detected by a terminal detection circuit during the “Rx detect” stage of the electronic product. However, the architecture of the terminal detection circuit is too complicated and the manufacturing cost of the terminal impedance detection circuits of the host and the electronic product is too high. In addition, the terminal detection circuits of manufacturers are different. For example, U.S. Pat. No. 7,161,388 discloses a remote receiver detection. Although the impedance between the host and the electronic product can be detected, however, the terminal detection circuits of manufacturers are not the same, resulting in the compatibility problem so that the signal between the terminal detection circuit of manufacturers cannot be correctly transmitted. Consequently, there is a need to develop a novel detection method to solve the aforementioned problems.